1. Field of the Invention
The present invention relates to a casting die.
2. Description of Related Art
Conventionally, in order to produce high quality castings by suppressing an occurrence of casting defects such as flow lines and cold shuts, casting dies applied with surface-machining or surface-treatment have been developed.
For example, the following Patent Literature 1 and 2 disclose a casting die whose surface is formed with grooves or dimples, in order to ensure a space (air gap) into which residual gas in a cavity can enter.
Further, the following Patent Literatures 3 and 4, in order to increase a contact angle of molten metal, disclose a casting die whose surface is coated with a carbon film including a nano-carbon.